What could be the cause of a painful red rash on the penis in a sexually active male, considering his female partner is showing symptoms of a bacterial infection?

Painful Red Rash on Penis with Partner's Bacterial Symptoms

This presentation most likely represents sexually transmitted urethritis (gonorrhea and/or chlamydia), and you should treat empirically with Ceftriaxone 250 mg IM single dose PLUS Doxycycline 100 mg orally twice daily for 10 days, even before test results return. 1

Immediate Diagnostic Approach

Perform these tests before initiating treatment:

• Gram stain of urethral discharge or intraurethral swab looking for ≥5 polymorphonuclear leukocytes per oil immersion field to confirm urethritis 1
• Urethral culture or nucleic acid amplification test (NAAT) for both N. gonorrhoeae and C. trachomatis 1
• First-void urine examination for leukocytes if urethral Gram stain is negative 1
• Syphilis serology as part of comprehensive STI screening 1

The key clinical point: sexually transmitted urethritis is usually accompanied by urethritis in the male partner, which is often asymptomatic 1. Your symptoms may be the first indication that both you and your partner have an STI.

Why Empiric Treatment is Critical

Do not wait for test results to begin treatment. The CDC guidelines explicitly recommend empiric therapy before culture results are available because:

• Current tests for C. trachomatis are not sufficiently sensitive to exclude infection 1
• Treatment prevents transmission to others and improves symptoms rapidly 1
• Your female partner's bacterial symptoms suggest she likely has pelvic inflammatory disease (PID), which requires urgent treatment to prevent permanent complications like infertility 1

Age-Based Treatment Algorithm

If you are under 35 years old (sexually active):

• Ceftriaxone 250 mg IM single dose AND Doxycycline 100 mg orally twice daily for 10 days 1, 2
• This covers both gonorrhea and chlamydia, the most common causes in this age group 1

If you are over 35 years old (and not sexually active):

• Consider enteric organisms like E. coli, especially if you have urinary symptoms or recent urinary procedures 3
• Fluoroquinolone monotherapy (e.g., Ofloxacin 300 mg orally twice daily for 10 days) would be appropriate 3, 2

However, given your partner has bacterial symptoms, sexually transmitted causes are most likely regardless of age 1.

Critical Management of Your Partner

Your female partner requires immediate evaluation and treatment for presumed PID. The CDC states that evaluation and treatment of sex partners is imperative because:

• High likelihood of urethral gonococcal or chlamydial infection in the male partner 1
• Risk of reinfection if partner is not treated 1
• Partners should be treated empirically with regimens effective against both infections regardless of test results 1

She needs urgent medical attention because untreated PID can cause:

• Tubo-ovarian abscess 1
• Chronic pelvic pain 1
• Ectopic pregnancy 1
• Infertility from tubal scarring 1

Alternative Diagnoses to Consider

If STI testing is negative and symptoms persist, consider:

• Trichomonas vaginalis (2-5% of NGU cases) - requires wet mount examination and culture 1, 4
• Ureaplasma urealyticum (20-40% of NGU cases) - may require extended erythromycin therapy 1
• Herpes simplex virus - look for vesicles or painful ulcers 1, 5
• Contact dermatitis or irritant reaction - but less likely given partner's symptoms 6

Follow-Up Requirements

Return for evaluation within 72 hours if:

• Fever develops 2
• Severe pain worsens 1, 3
• Symptoms don't improve within 3 days 3

Microbiologic re-examination 7-10 days after completing therapy is recommended to ensure persistent infection is cleared, particularly for C. trachomatis 1.

Rescreening 4-6 weeks after treatment helps detect reinfection, especially if partner was not adequately treated 1.

Common Pitfalls to Avoid

• Never treat only yourself without ensuring partner treatment - this leads to reinfection and continued transmission 1
• Don't assume negative initial tests exclude STI - sensitivity limitations mean empiric treatment is still warranted based on clinical presentation 1, 2
• Avoid single-agent therapy - must cover both gonorrhea and chlamydia in sexually active men under 35 1
• Don't delay treatment waiting for test results - complications in your partner may progress rapidly 1